Original Articles
Oxidative stress in asphyxiated term infants resuscitated with 100% oxygen,☆☆

https://doi.org/10.1067/mpd.2003.91Get rights and content

Abstract

Objective To test the hypothesis that resuscitation of asphyxiated infants with pure oxygen causes hyperoxemia and oxidative stress. Study design Asphyxiated term newborn infants (n = 106) were randomly resuscitated with room air (RAR = 51) or 100% oxygen (OxR = 55). The Apgar score, time of the first cry, and establishment of a sustained pattern of respiration were recorded. Assays performed included: blood gases; reduced glutathione (GSH) and oxidized glutathione (GSSG) in whole blood; glutathione-related enzyme activities; and superoxide dismutase activity (SOD) in erythrocytes. Results The RAR group needed less time of ventilation for resuscitation (5.3 ± 1.5 vs 6.8 ± 1.2 min; P < .05). Pure oxygen caused hyperoxemia (PO2, 126.3 ± 21.8 mm Hg) that did not occur with the use of room air (PO2, 72.2 ± 6.8 mm Hg). GSH was decreased and GSSG, the glutathione cycle enzymes, and SOD activities were increased in both asphyxiated groups. However, the 100% oxygen-resuscitated group showed significantly greater alterations that correlated positively with hyperoxemia. Conclusions Asphyxia causes oxidative stress in the perinatal period, and resuscitation with 100% oxygen causes hyperoxemia and increased oxidative stress. Because there are no advantages to resuscitation with 100% oxygen, room air may be preferred under certain circumstances for the resuscitation of asphyxiated neonates. (J Pediatr 2003;142:240-6)

Section snippets

Design

This is a randomized clinical trial, blinded for the gas source during resuscitation. Randomization was performed by assigning a sealed enveloped containing a computer generated random number plus a statement indicating the corresponding group (100% oxygen or room air) to each mother's record at admission to the obstetric ward before delivery. Eligible patients were recruited among term neonates (37-40 weeks' gestation) born at the Hospital Virgen del Consuelo that showed evident signs of

Results

There was an increased rate of cesarean delivery among the asphyxiated infants (72%) compared with the control group (32%) (Table I). In addition, significant differences because of the presence of fetal bradycardia, meconium-stained amniotic fluid, and the need for intubation occurred in the asphyxiated neonates compared with the control group.

The median Apgar score at 1 and 5 minutes was significantly lower in the asphyxiated newly born infants than in the control nonasphyxiated group (Table

Discussion

Oxidative stress is a physiologic event in the fetal-to-neonatal transition. In isolated hepatocytes from fetal and newborn rats, we found a dramatic decrease (15- to 20-fold) in the GSH/GSSG ratio, mainly because of a marked increase in the GSSG concentration in the fetal-to-neonatal transition.3 In addition, all the enzyme activities involved in the glutathione redox cycle increased during that transition, especially glutathione peroxidase and glutathione-s-transferase.3 Similar results were

Acknowledgements

We thank Marilyn R. Noyes for revising the manuscript.

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    Supported in part by the Annual Research Grant (1999) of the Sociedad Española de Neonatologia (to M. V.).

    ☆☆

    Reprint requests: Máximo Vento, PhD, MD, Servicio de Pediatría, Hospital Virgen del Consuelo, Callosa de Ensarriá, 15 bajo, E-46007 Valencia, Spain. E-mail: [email protected]

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